[taeric]

Turn signals can help folks that have to bike up a hill and want to indicate they are turning. :)

For the rest, I agree it increases the failure likelihood, but it is probably heavily mitigated in some cases by the fact that most of the power can be generated by the biker. These are not large gears, so the shifting capabilities probably don't require plugging in. And they should "fail to on" such that if they go dead on power, you just can't shift. Can still use the gear you are in.

[fishywang]

Turn signal would be useful. Just yesterday morning I was almost hit by a car when I was merging from bike lane to left turn lane.

[bamboozled]

You can just use your hands to indicate your intention to turn, this is done all over the world and AFAIK the accepted method of indicating without having any electronics.

[fishywang]

Yeah of course I did that, but some drivers just know nothing about cyclists. Give them something they are more familiar with would certainly help.